Techniques have been proposed for providing a network representation of a plurality of related keywords for a topic generated on the Internet or on an intranet. For example, a plurality of keywords co-occurring in a plurality of blogs may be extracted to provide a network representation thereof. Further, keywords close to a keyword specified by a user may be extracted to visualize a relationship among topical keywords. Furthermore, a user may specify a plurality of keywords and reputations related the keywords may be extracted to visualize a relationship among the keywords.
In another field, for example, as disclosed in Japanese Laid-open Patent Publication No. 2006-031577, an information search overlooking device performs a process of displaying a bird's eye view by extracting text information from information to be searched through, performing indexing of the extracted information, searching for pieces of information matching a search keyword given for a search input from a user, and arranging them at predetermined positions reflecting the degrees of matching between the matched pieces information and the search keyword and the relativity among the pieces of information to visualize them.
However, with the above conventional techniques, an overlook of the whole relation cannot be achieved. More specifically, with the technique of extracting keywords co-occurring in a plurality of blogs and providing a network presentation of the keywords, boundaries among the keywords cannot be clearly known because many networks having a lot of noise and no meaning with respect to a keyword specified by a user are included. With the technique of extracting keywords close to a keyword specified by a user to visualize a relationship among the keywords, a partial overlook of a portion of a business circle regarding a keyword specified by a user is possible but a whole overlook of the business circle is not possible. With the technique of specifying by a user a plurality of keywords and extracting reputations about the keywords to visualize a relationship among the keywords, the user has to specify a plurality of targets upon overlooking a business circle regarding the plurality of keywords. Therefore, the user has to have knowledge about the business circle and thus is unable to overlook the whole business circle. Similarly, with the technique disclosed in Japanese Laid-open Patent Publication No. 2006-031577, an overlook of the whole cannot be achieved.